Many industries including automotive, defense, aerospace, medical device, metalworking, fabrication, and assembly have requirements to mark parts or products. Direct part marking, laser marking, laser engraving and dot peen marking systems are used to mark parts for traceability and part verification. Current systems employ Windows based computers to control marking systems using commands that conform to the marker supplier's proprietary application programming interface (API).
Windows based computers are unsuitable for the modem day manufacturing floor, due to their need for software administration, and general lack of robustness. In manufacturing environments, programmable logic controllers (PLCs) are preferred. A PLC is a small, rugged computer, expressly designed for real-time control of industrial machines and devices. PLCs execute a control program, stored in programmable memory, to read sensors and perform machine control, timing, counting, and data handling. Ladder logic is widely used to write control programs for PLCs, where sequential control of a process or manufacturing operation is needed. Ladder logic represents a control program in the form of a ladder diagram, analogous to the circuit diagrams that describe hardware relay logic. Ladder logic has been adopted due to the wide variety of engineers and technicians that can understand and use it with little training. The ladder logic control program is often used in conjunction with an HMI (Human Machine Interface) program operating on a computer workstation.
Ladder logic can be thought of as a rule-based, rather than a procedural, language. A “rung” in the ladder represents a rule. When implemented with relays and other electromechanical devices, the various rules “execute” simultaneously and immediately. When implemented in a PLC, the rules are executed sequentially in a repeating loop (scan). By executing the loop rapidly, many times per second, the effect of simultaneous and immediate execution is achieved to within the time tolerance (“scan time”) required to execute all rungs in the “loop”.
Employing sensors to monitor external events, PLCs deliver rapid, real-time response to control machine operations. Software tools can provide visibility into the PLC control program's real-time operation as it executes, to find and fix problems. PLCs can have fixed, or modular I/O configurations for flexibility. A microprocessor internal to the PLC executes the ladder logic control program, and manages communication links to external equipment.
Current laser and dot peen marking systems employ supplier-specific proprietary APIs that are designed to be programmed using Windows-computer-based VB.Net and C# programming tools. The difficulty of programming these APIs with PLC ladder logic limits their functionality and hinders their use on the manufacturing floor. This problem is compounded by the proprietary nature of the APIs, as they do not conform to a common industry standard.
What is needed in the laser and dot peen marking industry is a system that conforms to common industry standards and facilitates the use of PLC ladder logic to program marking systems. This improves robustness, by allowing PLC's to replace Windows computers, and saves time and money, by no longer requiring engineers to leant proprietary APIs for each different marking system.
EtherNet/IP Industrial Protocol (EIP) is a flexible communication protocol specifically designed for industrial automation, and is an industry standard for interfacing PLCs, machines, and devices. EIP should not be confused with Ethernet network equipment in general. However, EIP has not been employed in the automated marking industry, because to-date, no marking system API's were available that supported EIP, as confirmed by a market search. EIP encapsulates the Control and Information Protocol (CIP), a widely implemented standard used in DeviceNet and ControlNet systems. CIP allows EIP and DeviceNet product developers, system integrators, and users to apply the same objects and profiles for plug-and-play interoperability among devices from different suppliers and across multiple networks. A common set of objects are used to control devices falling in the same device class, even from different manufacturers. The user benefits from interoperability among devices irrespective of the manufacturer or the device type.
Laser and dot peen marking systems are available from numerous manufacturers and provide a wide variety of marking functions. The difficulty of programming proprietary marking system APIs using PLC ladder logic hinders the use of more complex marking system functions. As a result, automated industrial marking solutions often do not realize the full potential of a laser or dot peen marker. What is needed is a system that provides easy, robust, and cost-effective PLC control of laser and dot peen marking-systems. The EIP Protocol Converter System is such a system